Twenty Years Later, Again
by AccidentProne24
Summary: Fifteen year old Phineas Flynn and the gang, decide to go twenty years in the future again to see what their lives would be like. Hoping to actually meet themselves. Their future selves have to hide some things from them in order to keep the timeline straight. Collaboration with FonceDarkness (Rated T to be safe)


_**A/N I have been working on this fic with FonceDarkness. It was actually her idea. I just added to it. We have been discussing this on social media and it turned into a roleplay. Thus. The fic 'Twenty Years Later, again' is born.**_

 _ **DISCLAIMER: I do not own Phineas and Ferb or any of the characters**_

* * *

 **PROLOGUE**

 **Danville, twenty years in the future…**

He walked through the door of the house on Maple Drive. "Hey, mom? Are you home? The redheaded adult scratched his head and then turned to the sound of a blender running in the kitchen. "Of course she didn't hear me…" he chuckled and walked into the kitchen.

Linda turned off the blender when she saw her youngest walk into the kitchen "oh, Phineas! I forgot you were stopping by today, dear" she smiled, "I made some margaritas, did you want one?"

"No thanks mom… Izzy is waiting for me in the car. I just stopped by to see if Dad still had that welder he said I could borrow last week… oh and…"

"NANA!" a redheaded girl rushed passed him and latched herself to Linda's waist, "I brought Danielle… she wanted to see you and Dad"

Linda reached down and gave the thirteen-year-old a hug "well, hello there!" she smiled as Danielle wrapped her arms around her neck. "I would love to spend the day with my youngest granddaughter!"

"I had hoped you would say that… now about that welder?"

"Oh… your father is in the garage working on the station wagon"

Phineas smiled and stuffed his hands into the pockets of his jeans before walking into the garage "hey, pops"

Lawrence wheeled himself out from under the station wagon "Phineas! So good to see you… how is the wife and my little Danny doing?"

"Danielle is in with mom. Isabella is waiting on me in the car, I'm actually here to pick up that welder that you said I could use to work on the T-bird?"

"OH! That's right" he chuckled and grabbed a shop towel, wiping the oil from his hands, "I nearly forgot. I've been trying to change the oil on this old girl all day" he walked to the closet and pulled out his old arc welder "here you are, my boy" he handed the equipment to his son and Phineas chuckled, "you're the best, Dad" he gave him a quick hug before wheeling the arc welder out of the garage and out to his Nissan.

Phineas loaded the welder into the trunk and turned to walk back to the garage "oh… mom offered to keep Danielle, so, I'll be back in a couple hours to pick her up." He rubbed the back of his neck, "that reminds me… Isabella and I are still going to come over for dinner… did you know if Ferb and Vanessa are going to be joining us as well?"

Lawrence smiled "he was talking about it… but I'm not for sure if he's actually going to stop by. I would love to see Jason and Kayle though and I'm sure Danielle would love someone to hang out with"

Phineas laughed "well, I think I'm going to give him a call and let him know I'll be here tonight" he winked and turned, walking out the open garage door once more, "I'll see you later tonight!"

"See you!"

He climbed into the car and looked over "Well, I got the arc welder for your car… so shall we?"

Isabella giggled "let me guess, you know what we're going to do today?"

He rolled his eyes, "Gosh, I was a goober back then… wasn't I?"

"Yes, yes you were"

* * *

 **Chapter One: The Plan**

 **Present Day Danville**

Fifteen-year-old Phineas was working on yet another invention with his stepbrother and their usual group of friends. They had already decided what they were going to do. He wanted to see what he looked like in twenty years. It was more for the sheer fact that he was starting to develop feelings for his very best friend, Isabella. Little known to everyone else, but Ferb.

"And that ought to do it!" the redhead said, dusting his hands off, "let's fire this puppy up and get to the future!"

"Haven't we already built a time machine before, Phineas?" Isabella asked, "or rather, refurbished…"

Phineas laughed "well, that is true. But, we haven't _actually_ built one! I wanted to see if we could build a working one from scratch!"

Isabella looked at Ferb, who just shrugged in reply.

"So does that not mean, that the one that we built could possibly not work?" Baljeet asked as he nervously tapped his fingers together, "what if we end up stuck in the other time!"

"Well, I did think of that… and we could ask out future selves for help! There is a chance that they did try this at our age, considering that they are _us_ just a bit older!"

"If you think about it, they would be in their thirties which means that they are most likely married and have kids" Ferb said with a shrug.

Phineas glanced at Isabella for a second and then chuckled "well, I kind of took that into consideration… and that would be really cool to see!"

Isabella blushed remembering when they wen twenty years in the future back when they were in grade-school. _I'll get to see if I end up with Phineas!_ Her heart started to beat faster. "Th-that sounds awesome!"

Ferb gave her a knowing smirk and flipped the switch on the machine, causing it to roar to life.

Phineas pumped his fist in the air "YEAH! It didn't explode, so that's a good sign" he grinned, "uh… that leaves the issue of getting bac home… one of us is going to have to stay here to man the controls and make sure that they don't disappear like everything else we've built…"

"I volunteer!" Baljeet raised his hand, "I don't…" he visibly cringed, "I mean, I do not want to run the risk of being stuck in another time"

"If Jeet is staying here, than so am I… besides, I already know I'm not going to change too much. Go have fun, find out if you and… uh… the girl you're crushing on… end up together"

Phineas looked at Buford "You don't want to see if you and Brigette get together?"

"Nope… the future is better left unknown to me. I don't want to jump the gun" he chuckled, "have fun!"

Phineas shrugged as he climbed into the first seat and held his hand out to Isabella "you coming?"

"Of course! I wouldn't miss it!" She jumped into the seat next to him, "Ferb?"

The silent teen climbed up into the machine and gave a thumbs up.

"Alright then… set the gauge to fifteen years from now…" Phineas flipped a couple of switches and turned a dial to fifteen, "okay… and here we go!" he pulled a lever and soon they were flying through a vortex of colors and light.

When the light dissipated, it was dark outside and they landed right outside the house. "Well… this looks like our house… but the color looks faded." He glanced to the driveway, "is that… is that a yellow convertible?"

"Why yes, yes it is… I wonder who that belong to."

"I think Dad may have had a midlife crisis or something…"

"What if it's yours?"

They both looked at Isabella and Phineas laughed "mine? I don't like yellow anything… if anything I would have a red one"

"I would have said Orange" Ferb said with a chuckle.

"I wonder who the white car belongs to" Isabella said, "The license plate says 'PFLYNN1'"

"Okay… I stand corrected" both boys said in unison.

"I say we go knock on the door…" Phineas said as he climbed out of the machine.

"So does that mean the convertible is mine?" Ferb asked.

"Or it could be Candace's" Isabella suggested.

As if right on cue, the light blue Nedlington Nymph pulled into the front of the house "never mind…"

* * *

 **In the Flynn-Fletcher House**

 **With the Adults**

"—and then Danielle almost burned a hole in the front yard!"

"Well, I'd say she takes after her father at that age" the green-haired adult chuckled as he took a bit from his tacos, "these are delicious, mom. Did you change the recipe?"

"Actually… Isabella added her own flare to them. I don't mind at all and I think that it was a splendid idea to throw parmesan into the meat"

"Thanks, mom… but your tacos are way better. I mean I've been coming over for taco night since I was a little girl" the raven-haired adult said as she took a drink from the margarita. Her husband put his hand on hers "don't be so modest… your cooking is spectacular, Izzy"

"Aww… Phineas, you're making me blush" she giggled.

"That's why you love me" he chuckled and kissed her softly on her lips.

"Umm… Mom, Dad… can you do that somewhere else?" Danielle said as she covered her eyes, "gross"

Linda laughed, "Oh, Danny… you may not mind so much in the future"

"Yeah… twenty years from now" Phineas added.

"Dad!"

The adults laughed at how red the eight-year-old was turning.

"Oh give her a break guys…" The brunette woman said, "Consider it a blessing that she doesn't like boys yet… unlike her mom at her age"

"Oh ha, ha" Isabella said, "yes I got a crush a little early, so what? I ended up marrying mine"

"Girls, please! Can we just have a normal dinner for once, without bringing up the past? After all, we should be extremely happy that she inherited her father's obliviousness" Ferb said as he sipped from the beer can in front of him.

"HEY! I wasn't oblivious! I was just not interested in girls so I wasn't… picking up… her…" he crossed his arms, childishly "okay I was oblivious, so shoot me"

"Oh, sweetie… don't be so hard on yourself… you were definitely worth the wait"

* * *

 **Adult Phineas POV**

I grinned, "well I appreciate that, babe" I stood and patted my full belly "wow, I'm stuffed… thanks for dinner mom. I'll take out the trash" I turned and walked into the kitchen, pulled the full bag of trash out of the kitchen trash can, and walked out the front door. What I saw made his jaw drop "what the f… are you kidding me right now?"

A teenage version of myself was preparing to ring the doorbell.

"Oh wow… you have facial hair, Phineas"

I glanced to the right to see a younger Isabella, staring at me and then noticed a younger Ferb standing next to the younger me.

I gulped and put my hand to my face "please tell me you didn't build a time machine from scratch…"

"Well, yeah we did actually… why?" the younger me asked.

"Because now you're stuck here for a while… if you don't believe me, go ahead and fire it up again" I crossed my arms, and waited while the younger me tried to fire up the time machine again. "He's right, Ferb. It's not starting!"

"I'm from the future! Of course I knew it wouldn't start up!" I scolded, "now I have to let mom know that you three will be staying with us for a couple of days" I rolled my eyes and sighed, "stay here… I have to prepare everyone for this"

I turned to go but then I heard the younger Isabella gasp _oh no…_ I turned as I heard her "you're married!"

"Yes, yes I am… was… but that's not important" I shook my head, I tried to keep myself from scratching my ear, that started to itch. I knew if I did, they would catch my bluff and find out that Phineas marries Isabella in the future. I smiled, "so… Isabella… you're probably going to be most comfortable with yourself so I'll let her know you're here as well" I turned to walk into the house and pulled out my phone, sending a quick text to my wife ' _time travelers… remove your wedding band and stick it in your pocket, then come around from the back and meet me at the door… but act like we're not together_ '

"Wait… what do you mean 'was'?" Isabella asked.

"Don't worry about it" I said.

"Hey, Phineas… what'cha…" perfect timing, love, "oh my god"

"hey Isabella… what brings you here?"

"I was visiting my mom and could smell the tacos… taco night?" I watched as she eyed the three teenagers, "oh… tonight's _that_ night"

"Yeah…" I smiled, "I need to talk to her in private for a moment, stay here" I said to the teenagers before Isabella and I walked into the backyard "we need to go prepare everyone for the time travelers… Ferb knows, so send him a text and have him tell Danielle not to blow our cover. That means that him and Vanessa need to fake not being together."

"That means that we won't be sleeping in the same bed tonight then…" she seemed a bit disappointed, "yeah… but it's for a good cause… huh… who would have thought that this is what they talked about when they disappeared into the backyard"

"Oh no… that means that the younger me is trying to listen through the gate" She ran to the gate and opened it "private, means private, fireside girl"

"Oops!"

I chuckled as I heard her scamper off, "do you think she heard anything?"

"I didn't when this happened to me fifteen years ago… so no… but we need to avoid any physical contact. Unless you forgot what happened when we saw _them_ kiss"

"You mean when _I_ saw them kiss" I said as I cleared my throat, "send that text and I'll bring the kids in"

"Gotcha… and Phineas? Before we have to separate for three days…"

"I want to kiss you more than anything right now… but you know that's a bad idea" I said turning my face away. I could see my wife's shoulders slump, "don't be like that… it's for their own good"

Isabella crossed her arms "I know… I just haven't spent any time apart from you since the day we said 'I do'" she pouted, "just one?"

"Fine" I looked around and everything seemed too familiar, "he's watching… but I think it's supposed to happen" I said quietly as I planted a passionate kiss on my wife's lips, "something to remember me by"

* * *

 **Teenage Phineas' POV**

 **(A few minutes earlier)**

I watched Isabella run away from the gate and decided to do some sneaking myself. I found the gate propped open slightly and sat on the side just listening.

"—she heard anything?" I heard the older me whisper. And then I heard the older Isabella giggle "I didn't when this happened to me fifteen years ago… so no… but we need to avoid any physical contact. Unless you forgot what happened when we saw _them_ kiss" my mouth went dry _they're faking this!?_ I listened more and heard "you mean when _I_ saw them kiss" I heard the older me say as he cleared his throat, "Send that text and I'll bring the kids in" I felt like I needed to run but I was frozen.

"—want to kiss you more than anything right now… but you know that's a bad idea" I glanced through the gate _wait… KISS!?_ I gulped and watched a bit. "don't be like that… it's for their own good"

I watched as she crossed her arms, "I know… I just haven't spent any time apart from you since the day we said 'I do'" I gulped _they're married!?_ "Just one?"

The adult me rolled his eyes and apparently gave in "Fine" he looked around and I could swear his eyes met mine. I stayed still, hoping he hadn't seen me, "he's watching… but I think it's supposed to happen" my jaw dropped _supposed to happen… was this where he saw him and her kiss?_ I wondered and then watched as he placed a deep and passionate kiss on her lips, "something to remember me by" I slowly began to back away from the gate _so that's who I marry… now that I know, does that mean that the Isabella from my time likes me? I can't risk jumping the gun…_ I sighed, _I'll just play along._

I walked over to the other two. "So?" Ferb asked.

"Nothing… they were just talking about how they were going to break it to mom and sleeping arrangements and whatnot" I resisted the urge to scratch my ear, hoping that they would believe me, but, then I felt my face get hot and knew I was turning red. _I cannot let them know that I saw future me and future Isabella, kiss…_

"Is something wrong Phineas?" Isabella asked and I shook my head, "I'm fine… I just… uh… I'm a bit upset that he… I mean me… is no longer married. I almost wonder who he was married to"

"Oh, I understand that feeling" I heard the sadness in Isabella's voice but didn't pry.

Ferb put a hand on her shoulder and she looked up at him with teary eyes.

I watched as the older me walked out of the backyard "okay, so we got everything settled. Isabella, you're going to stay with the Isabella from this time… Phineas, you're going to stay at my house with me and my daughter… you'll get to meet her when we go inside … and Ferb, you're going to stay with Ferb and his two boys, you'll meet them when we go inside as well"

"So I get to stay with my older self?"

I watched him nod "is that a bad thing?"

"No, I just have tons of questions for her"

I got the feeling it might be about who she ended up with, then again, I didn't see a ring on her finger. So, maybe she's pretending to have never gotten married. I knew the truth though. I was happy. It was exactly how I wanted it to be. _Wait a minute… I have a daughter!?_

"We can go inside now… that means you, lost-in-thought Flynn" I heard him chuckle and shook my head.

"I'm comin'" I said and followed him, Ferb, and Isabella into the house.

* * *

 _ **A/N I hope you enjoyed the first chapter. I will have the next one up sometime within next week.**_

 _ **Please R &R. I would like to hear what you thought.**_


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